Drop-out fuse structure with leaf spring in hinge assembly for providing a kickout force

ABSTRACT

A pivotally mounted fuse holder having a fusible element disposed therein is disposed between stationary contacts of a fuse structure. Upon blowing of the fusible element, a movable member in the fuse holder actuates a latching means in one of the stationary contacts to release the fuse holder from that contact. A leaf spring disposed in the other stationary contact, which also acts as a hinge for the fuse holder, then supplies a force to pivot the top part of the fuse holder to a drop-out position in which an electrically insulating gap is interposed between the stationary contacts.

[451 Oct. 15,1974

DROP-OUT FUSE STRUCTURE WITH LEAF SPRING IN HINGE ASSEMBLY FOR PROVIDING A KICKOUT FORCE Inventors: Harold L. Miller, West Elizabeth;

Woodrow G. Shaw, Export, both of Pa.

Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: Sept. 22, 1972 Appl. No.: 291,468

Assignee:

US. Cl. 337/171, 337/174 Int. Cl. H0lh 71/10 Field of Search 337/161-172, 337/174 References Cited UNITED STATES PATENTS 1/1949 Schultz 337/170 Gesellschap 337/171 Barta 337/174 X Primary ExaminerJ. D. Miller Assistant ExaminerFred E. Bell Attorney, Agent, or Firm-M. J. Moran [57] ABSTRACT A pivotally mounted fuse holder having a fusible element disposed therein is disposed between stationary contacts of a fuse structure. Upon blowing of the fusible element, a movable member in the fuse holder actuates a latching means in one of the stationary contacts to release the fuse holder from that contact. A leaf spring disposed in the other stationary contact, which also acts as a hinge for the fuse holder, then supplies a force to pivot the top part of the fuse holder to a drop-out position in which an electrically insulating gap is interposed between the stationary contacts.

2 Claims, 6 Drawing Figures PAKmum 1 5mm SHEU 20F 2 CROSS-REFERENCE TO RELATED APPLICATIONS The subject matter of the invention is related to copending and concurrently filed application Ser. No. 29l,467 Latch and Guide Assembly for A Drop-Out Fuse Structure filed by John W. Carothers.

BACKGROUND OF THE INVENTION 1. Field of the Invention:

This invention relates to circuit interrupters, and more particularly, to drop-out fuse structures.

2. Description of the Prior Art:

Prior drop-out fuse structures are exemplified by US. Pat. No. 3,447,114 issued May 27, 1969 to R. E. Fink et al. This prior art structure employs a relatively complicated combination kick-out action spring-latch assembly at the latching end of the fuse structure but has no kick out forcing means at the hinge assembly. It would be advantageous to have a spring in the hinge assembly to act independently or supplementally to provide a forcing action for causing fuse drop-out at appropriate times.

SUMMARY OF THE INVENTION According to the invention, an electric dropout fuse assembly having a generally vertically oriented base and spaced contact portions thereon has disposed thereon a generally cylindrical fuse body or unit having end ferrules for making electrical contact with the spaced contact portions and interconnected fusible element which may be surrounded by a protective structure such as a fuse housing or holder. The lower contact member of the dropout assembly comprises a hinge upon which one ferrule of the fuse may be pivotally disposed. Disposed adjacent the hinge contact is a leaf spring which engages a portion of the lower ferrule as the fuse unit is pivoted into an electrically conducting circuit protective position with respect to the upper and lower contacts. The upper contact assembly has a latching member therein so that when the fuse body or unit is placed or assembled in the previously described electrically conducting protective position, it is latched therein until the fuse blows, causing a release of the latch by a suitable means internal to the fuse, or the fuse is purposely pulled out of contact by a manual operation when desired. The previously described leaf spring becomes charged when the fuse body is placed in the previously described normal electrically conducting position. When the latch member is disengaged by an action related for example, to the blowing of the fuse, the spring forceexerted against the lower ferrule causes the fuse to rotate outwardly from the upper contact member to disengage the spent or blown fuse from the electrically conducting protective position. The leaf spring permits a significant simplification of a kickout or forcing member for a fuse drop-out assembly. In addition, it is disposed away from the latching contact of the fuse holder so that the unlatching and forcing mechanisms need not operate in proximity to each other where they may interfere with each other or where they may cause overcrowding of the relatively limited space in the upper fuse assembly contact.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference may be had to the preferred embodiment exemplary of the invention as shown in the accompanying drawings, in which:

FIG. 1 is a view in elevation, partially in section and partially broken away, of a high voltage dropout fuse structure which embodies the principles of the present invention and which is shown in a normally closed or operating position;

FIG. 2 is a view of the leaf spring employed in the embodiment of FIG. 1;

FIG. 3 is an enlarged view, partially broken away and in elevation, of details of the lower fuse holder portion of the embodiment of FIG. I, with the fuse in a partially opened position;

FIG. 4 is a view similar to FIG. 3, but with the fuse in the closed or normal operating position;

FIG. 5 is a sectional view in front elevation of a portion of a fuse structure similar to that shown in FIG. 4; and

FIG. 6 is a side elevation of another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and FIG. 1 in particular, a drop-out fuse structure 10 is shown including a base 11 which may be formed of metal and a pair 'of outwardly extending or projecting insulator support members 12 and 14 which are vertically spaced from one another along the associated base 11. Attached or fastened to the upper insulating support member 12 in a convenient manner is a latch assembly 16 which may comprise a suitable cover 18. Fastened to or secured to lower insulating support member 14 is a hinge assembly 20. Both the latch assembly 16 and the hinge assembly 20 have electrically conducting portions as part thereof which may be connected to an external electrical circuit which a fuse assembly 24 interposed and interconnected between latch assembly 16 and hinge assembly 20 may protect. Fuse assembly 24 may be of thetype which is described in greater detail in US. Pat. No. 3,401,247, issued Sept. 10, 1968 by C. W. Upton, Jr., C. C. Patterson and F. L. Cameron; US. Pat. No. 3,401,245, issued Sept. 10, 1968 by F. L. Cameron and US. Pat. No. 3,401,244, issued Sept. 10, 1968 by C. C. Patterson, all of which are assigned to the same assignee as the present application. More specifically, fuse unit 24 comprises a fuse holder 25 inside of which is disposed a fusible element 25F. Disposed on the upper end of fuse holder 25 is an upper end fitting, terminal or ferrule 26. Disposed on the lower end of fuse holer 25 is a lower end fitting, terminal or ferrule 28. Upper end fitting or ferrule 26 has disposed as part thereof an end portion 30 having an axial hole therein through which an axially movable member or plunger 32 may be actuated to protrude under certain conditions, one of the conditions being the fusing or blowing of the fuse element 25F. Also disposed adjacent the upper end ferrule or fitting 26 is an axially projecting portion 34 adapted to cooperate with a latching and/or forcing mechanism (not shown) in latch assembly 16. As an example, an appropriate latching mechanism within latch assembly 16 may grasp a portion of the axially projecting portion 34 to hold the fuse unit 24 in a vertical and operational position. In some instances, a force sufficient to drive fuse unit 24 out of contact with the electrically conducting portions in the upper latch assembly 16 may be directed against ferrule 26. A hook-eye 36 is also pivotally disposed on a portion of the upper end fitting 26 so that the fuse 24 may be manually forced into and out of electrical contact with portions of the upper latch assembly 16. With respect to latch assembly 16, it is to be understood that the latching and/or forcing portions of the latch assembly 16 may be of any convenient type. For example, latch assembly 16 may comprise a latching mechanism such as shown in previously referred to US. Pat. No. 3,447,114. As another example, the mechanism contained within the latch assembly 16 may comprise the mechanism shown and described in the previously referred to and copending application Ser. No. 291,467.

With respect to the lower hinge assembly 20, lower end'fitting or fuse ferrule 28 has disposed thereon a pair of radially projecting trunnions 38. Also disposed on member 28 is a sector shaped portion 40, a cylindrically projecting portion 42 transverse to the axis of the fuse holder 25 and a hinge lifting eye 44. All of the previously named ferrule portions may be integrally formed with the lower end ferrule 28 of fuse unit 24. Affixed to one portion of the lower hinge assembly is'a leaf spring member 46. Leaf spring member 46 may be conveniently secured to insulator 14 and hinge assembly 20 by means of a bolt, screw or similar fastening means 48. It can be seen that in certain instances, a portion of hinge lifting eye 44 maybe disposed against a portion of leaf spring or forcing member 46. Cushioning the fuse during an opening operation is also shown.

Referring now to FIG. 2, an enlarged view of leaf spring member 46 is shown. Spring member 46 may comprise a relatively long strip of spring steel having a generally flat or elongated portion 50 and a generally arcuate portion 52 adjacent to one end of portion 50. Adjacent to the other end of arcuate portion 52 may be a shorter flat portion 54, which is generally perpendicular or transverse to portion 50; and adjacent to the other end of portion 54 is a gently curving arcuate portion 56 which curves in a generally opposite direction to the arcuate portion 52 and which has a generally smaller radius of curvature than arcuate portion 52. Disposed against the opposite end or as part of the opposite end of elongated portion 50 is a sharply turned arcuate portion 58. A hole 59 may be conveniently formed in elongated portion 50 for the insertion of bolt 48 as shown in FIG. 1. In a preferred embodiment of the invention, the horizontal component of distance as viewed in FIG. 2 between the farthest end of portion 58 on the left and the centerline of hole 59 may be generally .84 inches. The horizontal component of distance between the farthest part of arcuate portion 58 and the portion 54 measured longitudinally in the same direction as the extension of flat portion 50 may be generally 2.59 inches. The radius of curvature of the arcuate portion 52 may be generally 0.75 inches. The radius of curvature of arcuate portion 56 may be generally 0.25 inches. The centerline for the radius of curvature for arcuate portion 52 may be disposed generally 1.13 inches vertically above the vertical extension of arcuate portion 58 and generally 1.75 inches to the right of the farthest horizontal extension of arcuate portion 58. The

radius of curvature of the arcuate portion 56 may extend generally 0.25 inches above the location of the centerline of the radius of curvature of arcuate section 52, and may be generally 0.19 inches to the right of the farthest horizontal extension of arcuate section 56. The farthest distance between arcuate portion 56 and arcuate portion 58 measured vertically may be generally 1.5 inches. The spring member may have a thickness of generally 0.093 inches and may be generally 1. inch wide, and as mentioned previously, may comprise stainless steel or any material having suitable resilient and structural properties for the purpose described.

Referring now to FIG. 3, an enlarged view of hinge assembly 20 is shown, with the fuse unit 24 in the open or electrically insulating position. It can be seen that trunnion 38 rests in slot 66 wherein it may pivot or rotate as the fuse is moved in a clockwise or counterclockwise direction. Arcuate portion 40 is disposed with respect to trunnion 38 so that a snub pin 60 disposed upon the inner side of frame 22 of hinge assembly 20 may be captured between the trunnion 38 and the sector shaped portion 40 as the fuse holder is moved in to or out of electrical contact with the upper latch assembly. This provides a lock or retaining means to keep the fuse holder from completely falling out of the hinge assembly as the fuse assembly is opened, and also provides a guiding channel so that the fuse holder may pivot easily. When the fuse holder has travelled as far in a clockwise direction as it can during a drop-out or disconnecting operation, an abutting portion 21 which is part of the lower left portion of ferrule 28 abuts against a portion of the pin hinge assembly, which will be described later. It is in this farthest rotated position, that hook-eye 44 may be conveniently engaged by any lifting means such as a hookstick and fuse unit 24 may be thereby lifted out of the hinge assembly 20. It will be seen that after a significant amount of rotation in the counterclockwise direction, the cylindrically shaped projecting portion 42 engages a portion of slot 64 in frame 22. This also helps to guide the fuse 24 during a later drop-out operation and it provides a stop for the movement of fuse structure 24 in the counterclockwise direction during an engaging operation. This can be seen by the fact that cylindrical portion 42 can rotate no further than the farthest left-most portion of slot 64 as shown in the figure. An integral part of lower ferrule or terminal 28 is an arcuate shaped contacting member 62 which may be rotated into electrical contact with a similar contact member 68 which is part of the hinge assembly 20. It will be noted that a stop pin 70 may be provided adjacent the inner arcuate portion of the resilient and flexible contact 68. When the fuse blows it falls (due to gravity after spring action is over) completely open to an inverse vertical position bouncing against bumper 47. A member is used to provide a pivot axis for a gravity cap 49 which falls over the bottom of the fuse holder when it falls completely open in order to keep out rain, etc. It hangs directly down when the fuse is in the closed position. The previously described leaf spring forcing member 46 is shown disposed adjacent to the back portion of the hinge assembly 20 by means of fastening means 48. It will be noted that in this position or when the fuse is in the drop-out position forcing element or spring member 46 takes on its relaxed, natural shape.

Referring now to FIG. 4, fuse unit 24 is shown in a nearly vertical position or in an operational position where electrical current may flow through a terminal (not shown) to contact portion 62 on ferrule 28 and through an electrical fuse element 25F as shown in FIG. 1 contained within fuse holder 25 to the latch assembly 16 (not shown) and to the external circuit (not shown) to complete the electrical circuit. It will be noted that in this vertical position or electrically conducting position, fuse structure 24 has been rotated in a counterclockwise direction from the position shown in FIG. 3. The pivot upon which this rotation takes place comprises the trunnion 38 rotating against the bottom portion of groove 66. During this rotation, arcuate portion 40 has rotated past snub pin 60, and projecting portion 42 has rotated as far as it can go into slot 64. It will be noted that this rotation in the counterclockwise direction causes a portion 43 of hinge lifting member 44 to engage forcing member or leaf spring 46 to cause leaf spring 46 to be placed in a charged position. It can be seen by examining FIG. 4 and FIG. 2 that the arcuate portion 52 as shown in FIG. 2 has been flattened or given a larger radius of curvature by the action of hinge lifting eye 44 being rotated against the resilient spring member 46 during the rotation of fuse unit 24 into the electrically conducting orientation previously described. Since spring element 46 has been charged, it exerts a force 71 against portion 43 of hinge lifting eye 44 so that, should the latched portion of fuse unit 24 become disengaged for any reason, such as the blowing of the fuse element 25F contained within holder 25, fuse unit 24 will rotate in a clockwise direction to a disconnected position because of the exertion of the force of charge spring member 46 against the hinge lifting eye 44. It is to be understood that spring member 46 may be the exclusive forcing member for causing the rotation of fuse unit 24 in the clockwise direction, or it may be used supplementally or in combination with known forcing mechanisms in the latch assembly 16 such as described in the previously mentioned copending application Ser. No. 291,467, or the latch assembly described in the previously mentioned US. Pat. No. 3,447,114.

It has been found experimentally that, depending upon the size and strength of the spring material of leaf spring 46, the spring 46 can act on fuse member 24 for up to approximately 30 of angular rotation in the clockwise direction during the opening operation.

Referring now to FIG. 5, a sectional front view of fuse element as depicted in FIG. 4 is shown. Additionally shown is a base 11 for hinge assembly with base 11 having openings 82 for the insertion of fastening means, such as bolts or screws. The bolts or screws may be attached or fastened to structural pieces for mounting the fuse including the base assembly 11 to an appropriate foundation or support means. Fuse structure 10 as shown in FIG. 5 includes a lower terminal 100 to which may be attached or fastened a conductor from an external electrical circuit which the fuse structure 10 is intended to protect. Fuse structure 10 is shown disposed in hinge assembly 20. Note the outward flaring of portions 22A of frame 22 of hinge as-. sembly 20. Also note the cylindrically projecting portions 42 which as has been described previously assist in maintaining the fuse structure 24 in its electrically conducting position.

Referring now to FIG. 6, another embodiment of the invention is depicted. In this embodiment, a base 11' is shown which is similar to the base 11 shown in FIG. 5.

Disposed on base 11 are two electrically insulating support members 1 and 14', electrically insulating member 12' being the upper member and electrically insulating support member 14' being the lower member. The hinge member 20' which is the same as hinge member 20 as shown in FIGS., 1, 3 and 4 is shown attached to lower electrically insulating support member 14'. Fuse assembly 10 which is similar to fuse assembly 10 shown in FIG. 1 includes a fuse 24' the upper portion of which is in electrical contact with a latch assembly 16' which is similar to latch assembly 16 shown in FIG. 1 but which is, in this embodiment of the invention, a latch assembly such as described in the previously mentioned copending application Ser. No. 291,467. The hook portion 36' is shown on the upper portion of holder 24' and is useful in moving fuse holder 24' out of electrical contact with latch assembly 16' or into electrical contact with latch assembly 16'. Latch assembly 16' is fastened to electrically insulating support member 12 in a similar manner to which latch assembly 16 is attached, or fastened or secured to insulating support member 12 shown in FIG. 1.

It is to be understood that the drop-out fuse structure 10 may be diposed in other orientations than shown. For example, the fuse structure may be disposed in a horizontal orientation and the spring contact of the spring member 46 adjusted accordingly to cause clockwise rotation of the fuse during an opening cycle. It should also be understood that the relative placement of the hinge assembly 20 and the latch assembly 16 may be reversed, provided sufficient extensions in grooves 66 and 64 are provided so that the fuse unit 24 will not fall out of hinge assembly 20 during an opening operation due to the effect of gravity. It should also be understood that the support insulators 12 and 14 may be wholly or partially comprised of porcelain material, the fuse element may be oriented at any angle between the horizontal and vertical.

The apparatus embodying the teachings of this application have many advantages, one of which is the fact that spring member 46 need not necessarily be an element in the electrically conducting path between the fuse and the external electrical circuit, although, it may be if such is desired. Since it is not required to be a member or part of the electrically conducting path, the structural and resilient properties of the spring may be maximized and the electrically conducting properties may be minimized. Another advantage of the invention lies in the fact that the spring may be used supplementally with other spring functions in the latch assembly. This is useful in some ice-breaking operations where ice may cause the fuse to be jammed into an electrically conducting, primarily vertical orientation in some outdoor uses for the fuse unit. Another advantage lies in the fact that the forcing member or leaf spring for the drop-out fuse is envisioned to be disposed in the hinge assembly rather than in the latch assembly so that the latch mechanism and forcing mechanismneed not occupy the same relatively small area or space of the fuse structure. This splitting of the forcing function and latching function alleviates many of the problems that occur with crowding in a fuse structure such as mechanical fouling. Another advantage of the present invention is its relative simplicity since the spring comprises a single unitary piece. Another advantage lies in the fact that the spring member 46 may operate close to the trunnion members 38 and exert force against the lever arm comprising the trunnions 38, the cylindrical portion 42 and lifting eye 44 relatively long after the top ferrule 26 has completely disengaged from all portions of the latch assembly 16. This means that the forcing function may be exerted over a longer rotational portion of the dropout cycle, and that it may be exerted upon the spring member even after all the chance of electrical conduction has been eliminated by the providing of insulating space between ferrule 26 and latch assembly 16.

We claim:

1. A fuse drop-out assembly, comprising:

A. a support member for supporting parts of said fuse drop-out assembly;

B. a fuse means including:

a fusible element,

a fuse holder in which said fusible element is disposed,

a first electrically conducting ferrule disposed on a first portion of said fuse holder and electrically connected to a first portion of said fusible element,

a second electrically conducting ferrule disposed on another portion of said fuse holder, spaced from said first portion of said fuse holder and electrically connected to a second portion of said fusible element spaced from said first portion of said fusible element, and including as part thereof a second-ferrule force transmitting member, a pivot member disposed on said secondary electrically conducting ferrule, said pivot member being adapted to allow said interconnected first and second ferrules, and said fuse holder to rotate thereabout;

C. a first bracket means disposed on said support member, and adapted to engage said first ferrule of said fuse means when said fuse means is disposed in said fuse drop-out assembly in a manner to protect anexternal electrical circuit, said first bracket means including an electrically conducting member disposed in said first bracket to electrically interconnect a portion of said external electrical circuit and said first ferrule when said fuse is disposed in said fuse assembly to protect said external circuit; and

D. a second bracket means disposed on said support member and spaced from said first bracket means in engagement with said pivot member of said second ferrule of said fuse means including:

an electrically conducting member disposed in said second bracket means to electrically interconnect another portion of said external electrical circuit and said second ferrule,

a resilient spring member disposed adjacent a portion of said second bracket means, said resilient spring member having a generally flat portion and adjacent thereto a generally arcuate portion having a predetermined radius of curvature, said flat portion being the portion disposed adjacent said second bracket means and being fastened thereto, said resilient spring member not being significantly electrically conductive to said external electrical circuit when compared with the conductance of other parallel conductive paths of said second bracket means and said second ferrule, said spring member being chargeable by said second-ferrule force transmitting member and residing thereagainst while said fuse is disposed in said fuse assembly in a position to protect said external circuit, said arcuate portion being disposed closer to said support member after said charging of said resilient spring member than when said resilient member is in an unchanged state, said radius of curvature of said arcuate portion being larger than said predetermined value as a result thereof, said spring member being dischargeable against said second ferrule force transmitting member after fusing to thus move said second-ferrule force transmitting member to thus rotate said second ferrule to thus disengage said first ferrule from said first bracket means and thereby provide an electrically insulating gap between said first and said second bracket means.

2. The combination as claimed in claim 1 wherein said second ferrule comprises a generally cylindrically shaped body having a longitudinal axis, said fuse holder comprises a generally tubular body having a longitudinal axis generally coinciding with the longitudinal axis of said body of said second ferrule, said second ferrule comprising spaced pivot members disposed on generally opposite portions of said cylindrically shaped body of said second ferrule generally transverse to said axis, said second bracket having corresponding openings in which said pivot members are disposed so that said fuse means is generally rotatable about said pivot members in said openings in said brackets. 

1. A fuse drop-out assembly, comprising: A. a support member for supporting parts of said fuse drop-out assembly; B. a fuse means including: a fusible element, a fuse holder in which said fusible element is disposed, a first electrically conducting ferrule disposed on a first portion of said fuse holder and electrically connected to a first portion of said fusible element, a second electrically conducting ferrule disposed on another portion of said fuse holder, spaced from said first portion of said fuse holder and electrically connected to a second portion of said fusible element spaced from said first portion of said fusible element, and including as part thereof a second-ferrule force transmitting member, a pivot member disposed on said secondary electrically conducting ferrule, said pivot member being adapted to allow said interconnected first and second ferrules, and said fuse holder to rotate thereabout; C. a first bracket means disposed on said support member, and adapted to engage said first ferrule of said fuse means when said fuse means is disposed in said fuse drop-out assembly in a manner to protect an external electrical circuit, said first bracket means including an electrically conducting member disposed in said first bracket to electrically interconnect a portion of said external electrical circuit and said first ferrule when said fuse is disposed in said fuse assembly to protect said external circuit; anD D. a second bracket means disposed on said support member and spaced from said first bracket means in engagement with said pivot member of said second ferrule of said fuse means including: an electrically conducting member disposed in said second bracket means to electrically interconnect another portion of said external electrical circuit and said second ferrule, a resilient spring member disposed adjacent a portion of said second bracket means, said resilient spring member having a generally flat portion and adjacent thereto a generally arcuate portion having a predetermined radius of curvature, said flat portion being the portion disposed adjacent said second bracket means and being fastened thereto, said resilient spring member not being significantly electrically conductive to said external electrical circuit when compared with the conductance of other parallel conductive paths of said second bracket means and said second ferrule, said spring member being chargeable by said second-ferrule force transmitting member and residing thereagainst while said fuse is disposed in said fuse assembly in a position to protect said external circuit, said arcuate portion being disposed closer to said support member after said charging of said resilient spring member than when said resilient member is in an unchanged state, said radius of curvature of said arcuate portion being larger than said predetermined value as a result thereof, said spring member being dischargeable against said second-ferrule force transmitting member after fusing to thus move said second-ferrule force transmitting member to thus rotate said second ferrule to thus disengage said first ferrule from said first bracket means and thereby provide an electrically insulating gap between said first and said second bracket means.
 2. The combination as claimed in claim 1 wherein said second ferrule comprises a generally cylindrically shaped body having a longitudinal axis, said fuse holder comprises a generally tubular body having a longitudinal axis generally coinciding with the longitudinal axis of said body of said second ferrule, said second ferrule comprising spaced pivot members disposed on generally opposite portions of said cylindrically shaped body of said second ferrule generally transverse to said axis, said second bracket having corresponding openings in which said pivot members are disposed so that said fuse means is generally rotatable about said pivot members in said openings in said brackets. 